Intracoronary Doppler Research Articles

Simultaneous intracoronary ultrasound and Doppler flow studies distinguish flow-mediated from receptor-mediated endothelial responses.

Abnormalities in vascular endothelial function, which occur early in atherosclerosis, may play an etiologic role in the development of the disease or represent a marker for the extent of atherosclerosis. Endothelial dysfunction, usually characterized by demonstration of decreased endothelium-dependent vasorelaxation, may be a sensitive and specific method to detect vascular disease in its earliest stages. In this context, separation of abnormalities in receptor-mediated and flow-mediated endothelium-dependent vasodilatory responses may allow for the most accurate characterization of endothelial dysfunction. In 35 patients undergoing routine annual cardiac catheterization after heart transplantation, changes in epicardial lumen area and coronary blood flow in response to intracoronary administration of adenosine, acetylcholine, and nitroglycerin were measured simultaneously using an intravascular ultrasound (IVUS) catheter positioned over a Doppler flow wire in the left anterior descending coronary artery. The combination of these techniques allowed for distinction between receptor-mediated and flow-mediated endothelium-dependent vascular responses. Peak flow with the endothelium-independent resistance vessel dilator adenosine occurred at 18+/-2 sec; the maximal lumen area response occurred later, at 43+/-11 sec (P < 0.001). Acetylcholine, an endothelium-dependent small- and large-vessel vasodilator, caused an immediate increase in both flow and lumen area, but a second peak of dilation was observed, and maximal area occurred 46 sec after maximal flow (54+/-14 vs. 100+/-26 sec, P < 0.001). Simultaneous IVUS and Doppler flow measurements after infusion of vasoactive agents allows for distinction between and evaluation of the relative contribution of agonist-mediated and flow-mediated responses, which may offer important and unique insights into coronary endothelial function.

Assessment of ambiguous coronary lesions by intravascular ultrasound.

Until recently, coronary angiography has been regarded as the 'gold standard' for visualizing and quantifying coronary artery disease. Coronary angiography, however, is a luminographic technique revealing only the inner lumen of the coronary artery. In contrast, intravascular ultrasound investigations yield a detailed morphological description of the vessel wall and plaque characteristics. Based on these analyses, new insights into the pathogenesis of atherosclerotic coronary disease have evolved, including the remodeling phenomena. Thus, nowadays intravascular ultrasound can be regarded as the new 'gold standard' for the morphological assessment of lesion severity during cardiac catheterizations. Likewise, intracoronary Doppler and intracoronary pressure measurements have demonstrated their superiority in the functional assessment of coronary stenoses. Intravascular ultrasound investigations can be performed with high success and low complication rates. The present manuscript concentrates on the value of IVUS for the assessment of ambiguous lesions. Several forms of ambiguous lesions based on the angiographic appearance, i.e. intermediate lesion with undetermined stenosis severity, aneurysmatic widening of the coronary segment, ostial lesions, branching vessels, vessel tortuosity, main stem lesions, focal spasm, sites of plaque rupture, dissections, unclear haziness and contrast density changes are discussed and illustrated by respective angiographic and IVUS examples. Both the advantages and the limitations of angiographic and intravascular ultrasound examination are discussed in detail. In conclusion, additional intravascular ultrasound examination helps to diagnose accurately the underlying atherosclerotic disease, to define lesion characteristics and to optimize individual patient care and cost with respect to diagnostic catheterizations and coronary interventions.

Assessment of coronary artery stenosis with intracoronary Doppler guide wire and modified continuity equation method ; A comparison with dipyridamole stress Thallium-201 SPECT

Assessment of coronary artery stenosis with intracoronary Doppler guide wire and modified continuity equation method ; A comparison with dipyridamole stress Thallium-201 SPECT

A Computer Model for the Prediction of Left Epicardial Coronary Blood Flow in Normal, Stenotic and Bypassed Coronary Arteries, by Single or Sequential Grafting

This article describes a computer model for calculating left epicardial coronary blood pressure and flow waveforms of a right dominant coronary circulation. Using the geometry of 16 vascular branches and employing the one-dimensional Navier—Stokes equations the model allows for the prediction of blood pressure and flow patterns in normal and stenosed vessels. This model was also used to predict the haemodynamic changes observed after insertion of two single saphenous vein bypass grafts, as compared with the corresponding changes after insertion of a sequential (snake-like) saphenous graft. In normal vessels during systole and diastole, the pressure and the flow waveforms obtained showed patterns that correlate very well with the findings observed by other investigators using intracoronary flowmeter or Doppler velocimeter techniques. In coronary artery disease (90% stenoses in LAD and diagonal branch 1), the authors' main contribution is the reconfirmation of a previously described finding of systolic flow rises in stenotic segments. This finding seems to be an important compensatory mechanism, in contrast to normal coronary vessels, which maintain a mainly diastolic flow pattern. The introduction of single or sequential bypass grafts leads to pressure and flow restoration after graft revascularization. Besides this finding, the general concept of a diastolic flow restoration post-stenotically, in the previously decreased and systolic augmented flow areas, is also observed. The two revascularization methods were also compared with regard to their specific advantages, disadvantages and indications and were also extensively compared with several in vivo studies.

A computer model for the prediction of left epicardial coronary blood flow in normal, stenotic and bypassed coronary arteries, by single or sequential grafting

This article describes a computer model for calculating left epicardial coronary blood pressure and flow waveforms of a right dominant coronary circulation. Using the geometry of 16 vascular branches and employing the one-dimensional Navier–Stokes equations the model allows for the prediction of blood pressure and flow patterns in normal and stenosed vessels. This model was also used to predict the haemodynamic changes observed after insertion of two single saphenous vein bypass grafts, as compared with the corresponding changes after insertion of a sequential (snake-like) saphenous graft. In normal vessels during systole and diastole, the pressure and the flow waveforms obtained showed patterns that correlate very well with the findings observed by other investigators using intracoronary flowmeter or Doppler velocimeter techniques. In coronary artery disease (90% stenoses in LAD and diagonal branch 1), the authors' main contribution is the reconfirmation of a previously described finding of systolic flow rises in stenotic segments. This finding seems to be an important compensatory mechanism, in contrast to normal coronary vessels, which maintain a mainly diastolic flow pattern. The introduction of single or sequential bypass grafts leads to pressure and flow restoration after graft revascularization. Besides this finding, the general concept of a diastolic flow restoration post-stenotically, in the previously decreased and systolic augmented flow areas, is also observed. The two revascularization methods were also compared with regard to their specific advantages, disadvantages and indications and were also extensively compared with several in vivo studies.

Hemodynamic and Coronary Effects of the Endothelin Antagonist Bosentan in Patients With Coronary Artery Disease

Endothelin is a potent endothelium-derived vasoconstrictor peptide with proliferative properties. Elevated levels of the peptide occur in coronary artery disease; however, its pathophysiological role as a regulator of coronary tone and structure is uncertain. Endothelin-receptor antagonists are specific tools to clarify this issue and might be useful in the treatment of coronary artery disease. In a double-blind, placebo-controlled randomized study, we investigated the effects of the ETA/ETB endothelin-receptor antagonist bosentan or placebo on systemic and coronary hemodynamics in 28 patients with angiographically documented stable coronary artery disease by quantitative coronary angiography and an intracoronary Doppler guidewire. Bosentan 200 mg IV decreased systolic blood pressure (P<0. 05), whereas heart rate increased slightly (P<0.05). Coronary diameter increased, particularly in vessels with no or mild angiographic changes (P<0.01). Glycerol trinitrate did not further dilate these segments, whereas coronary diameter increased significantly after nitrate in the placebo group. The increase in coronary diameter after bosentan correlated inversely with plasma LDL-cholesterol levels (P<0.01) in both stenotic and angiographically normal coronary segments. Coronary flow velocity did not change. Bosentan was well tolerated. Endogenous endothelin exerts a vasoconstrictor tone in epicardial coronary arteries of patients with coronary artery disease, as evidenced by the vasodilation exerted by the combined ETA/ETB endothelin-receptor antagonist bosentan under acute conditions. Bosentan can safely be given to these patients. Hence, further long-term studies are necessary to determine the therapeutic potential of endothelin-receptor antagonists in patients with coronary artery disease.

Coronary collateral quantitation in patients with coronary artery disease using intravascular flow velocity or pressure measurements

Objectives. This study evaluated two methods for the quantitative measurement of collaterals using intracoronary (IC) blood flow velocity or pressure measurements.Background. The extent of myocardial necrosis after coronary artery occlusion is substantially influenced by the collateral circulation. So far, qualitative methods have been available to assess the human coronary collateral circulation, thus restraining the conclusive investigation of, for example, therapies to promote collateral development.Methods. Fifty-one patients with a coronary artery stenosis to be treated by percutaneous transluminal coronary angioplasty (PTCA) were investigated using IC PTCA guidewire-based Doppler and pressure sensors positioned distal to the stenosis. Simultaneous measurements of aortic pressure, IC velocity and pressure distal to the stenosis during and after PTCA provided the variables for calculating collateral flow indices (CFIvand CFIp) that express collateral flow as a fraction of flow via the patent vessel. Both CFIvand CFIpwere compared with conventional methods for collateral assessment, among them ST-segment changes >1 mm on IC and surface electrocardiogram (ECG) at PTCA. Also, CFIvand CFIpwere compared with each other.Results. In 11 patients without ECG signs of ischemia during PTCA (sufficient collaterals), relative collateral flow amounted to 46% as determined by Doppler and pressure wire. Patients with insufficient collaterals (n = 40) had relative collateral flow values of 18%. Using a threshold of CFI = 30%, sufficient and insufficient collaterals could be diagnosed with 100% sensitivity and 93% specificity by IC Doppler, and 75% sensitivity and 92% specificity by IC pressure measurements. The agreement between Doppler and pressure measurements was good: CFIv= 0.08 + 0.8 CFIp, r = 0.80, p = 0.0001.Conclusions. Intracoronary flow velocity or pressure measurements during routine PTCA represent an accurate and, at last, quantitative method for assessing the coronary collateral circulation in humans.

New imaging methods for visualizing coronary arteries

Techniques in the field of coronary artery imaging can be divided into two groups: invasive and non-invasive methods. Apart from the conventional coronary artery angiography, invasive methods include intracoronary ultrasound, intracoronary angioscopy, and optical coherence tomography. Non-invasive methods include magnetic resonance tomography, synchrotron-coronary angiography, and electron beam computed tomography. In the late 1980s, intracoronary ultrasound has come into clinical practice. It offers a real-time, cross-sectional image of the coronary artery in high resolution. Coronary arteries enlarge in the presence of atherosclerotic plaque formation in order to compensate for luminal narrowing caused by plaque formation (remodeling). With coronary angiography, the plaque formation cannot be detected until a lumen reduction of about 40-45%. With intravascular ultrasound, the early stages of atherosclerosis can clearly be demonstrated. In combination with the intracoronary Doppler technique, syndrome X can be differentiated. Another important role of intracoronary ultrasound in the diagnosis of coronary artery disease is to guide coronary interventions and to assess the result of coronary interventions especially to evaluate the result of stent implantation. Due to the clinical use of intracoronary ultrasound and the guidance of high pressure stent implantation, the incidence of acute stent thrombosis has decreased to about 1%. Coronary angioscopy portrays the surface of the vessel lumen. It is helpful to identify the mural thrombus especially to differentiate fresh and chronic thrombus formation. Magnetic resonance tomography is able to image the coronary arterial contour of the proximal segment. With today's gating technique, it is possible to portray the whole coronary tree and avoid disturbances resulting from the heart beat and respiration. Electron beam computed tomography is a very promising technique in screening for coronary artery disease. It is a very sensitive method to identify coronary calcification and, thus, to detect atherosclerotic plaque. Studies have shown that the presence of calcification almost invariably indicates the presence of coronary artery disease and that the absence of calcification can nearly rule out significant coronary artery disease. Moreover, a close correlation exists between the amount of calcification and the severity of coronary artery disease. Additionally, in combination with contrast injection, coronary artery perfusion can be evaluated. This is important to assess the conductance of coronary stent and bypass graft.

Assessment of intraindividual variability of coronary flow reserve in angiographically normal coronary arteries in transplant recipients: a study with intracoronary doppler and intravascular ultrasound

THE development of transplant coronary artery disease (TxCAD) is the major factor limiting long term survival after heart transplantation (HTx). In addition to the morphologic evaluation of TxCAD by angiography and intravascular ultrasound (IVUS), coronary flow reserve (CFR) is used as a functional parameter to assess the hemodynamic relevance of the disease. In most reports on patients after HTx, CFR was determined in a single epicardial artery and this measurement was considered representative for global graft function. The purpose of this study was to assess the intraindividual difference of the CFR values between two coronary arteries in patients after heart transplantation.

Coronary flow reserve may predict myocardial recovery after myocardial infarction in patients with TIMI grade 3 flow

Background The aim of the study was to determine whether the recovery of global and regional left ventricular function after successful percutaneous transluminal angioplasty (PTCA) could be predicted by measuring coronary flow reserve before performing the intervention.Methods and Results Thirty-two patients underwent PTCA 6.9 ± 3.4 days after a recent myocardial infarction. Coronary flow reserve was determined in the infarct-related artery before PTCA by using an intracoronary Doppler tipped wire. Global and regional wall motion were determined by 2-dimensional echocardiography before the Flowire study and again 7 weeks after the angioplasty. Whereas the global and regional wall motion score indices improved in 20 patients (recovery group), they deteriorated or did not change in 9 patients (nonrecovery group). Coronary flow reserve distal to the lesion in the infarct-related artery was significantly higher in the recovery group (1.43 ± 0.57 vs 0.98 ± 0.70, P =.0001). Coronary flow reserve distal to the lesion in the infarct-related artery was <1.1 in patients whose global or regional left ventricular function did not improve at follow-up, whereas flow reserve ranged between 1.1. and 1.8 while patients in whom left ventricular function improved.Conclusions These results suggest that the absence of inducible coronary flow reserve may predict failure of left ventricular systolic function to improve between the first and sixth week after infarction. Measurement of flow reserve with a Flowire at the time of diagnostic angiography after recent myocardial infarction may ultimately prove helpful in deciding whether to proceed with revascularization. (Am Heart J 1998;136:335-44.)

Improved Assessment of Coronary Stenosis Severity Using the Relative Flow Velocity Reserve

Myocardial fractional flow reserve (FFR) is based on pressure measurements. We have now sought to establish a Doppler-based concept of relative flow velocity reserve (RFVR) for the functional assessment of stenosis severity in epicardial coronary arteries. A clear threshold value to discriminate the functional severity of a coronary stenosis does not exist for coronary flow velocity reserve (CVR) based on intracoronary Doppler measurements. In contrast, the concept of FFR, which is based on intracoronary pressure measurements, has been extensively validated. An FFR value below 0.75 reliably indicates a significant stenosis. RFVR is calculated as the ratio between distal CVR in the stenosed target vessel and distal CVR in a nonstenotic reference vessel. In 21 patients, RFVR was determined in 24 target vessels by use of intracoronary adenosine and correlated to the FFR, determined as the ratio of mean poststenotic to aortic pressures, in the target vessel. Stenosis severity was classified according to quantitative coronary angiography analysis. Reference diameter was 3.0+/-0.4 mm (mean+/-SD), and area stenosis was 74+/-15% (range, 40% to 95%). CVRs in the target and reference vessels were 2.1+/-0.5 and 2.6+/-0.7, respectively. FFR ranged from 0.49 to 0.99 (mean, 0.81+/-0.15) and RFVR from 0.53 to 1.0 (mean, 0.82+/-0.13). Poststenotic CVR did not correlate with either percent area stenosis (r=0.27, P=NS) or FFR (r=0.33, P=NS). In contrast, FFR as well as RFVR showed a curvilinear relation to percent area stenosis (r=0.89, P<0.0001 and r=0.79, P<0.0001, respectively). There was a close linear correlation between FFR and RFVR (r=0.91, P<0.0001). RFVR correlates closely to FFR and to percent area stenosis, whereas the correlation of CVR with FFR and percent area stenosis is rather poor. RFVR is a promising new concept for assessment of coronary stenosis severity and clinical decision making based on Doppler measurements.

Current concepts of coronary flow reserve for clinical decision making during cardiac catheterization

Measurements of coronary flow reserve, once used only for research, have gained wide acceptance as an additional diagnostic approach in the decision-making process of diagnostic cardiac catheterization and coronary interventions. Apart from the noninvasive determination of coronary flow reserve, intracoronary Doppler flow wires have facilitated decision making in the catheterization laboratory. Different techniques, unstandardized procedures, and data from uncomparable patient populations have remained a confounding factor. This review examines current concepts of coronary flow reserve as well as methodologic considerations and pitfalls. Applications of coronary flow reserve for periinterventional assessment are evaluated on the background of practical guidance. According to a detailed examination of arterial structure and function, a normal coronary flow reserve exceeds a value of 3.0. Values below 3.0 suggest involvement of microvascular disease caused by functional or structural alterations. The influences of various factors such as age, hemodynamics, hypercholesterolemia, hypertrophy, hypertension, syndrome X, and coronary artery disease are discussed in relation to the effect on coronary flow reserve. From available information, measurements of coronary flow reserve are an adjunct to current interventional technology to optimize individual patient care. Further efforts should be undertaken to incorporate these new methods into our routine clinical decision making. (Am Heart J 1998;136:136-49.)

Coronary endothelial dysfunction in patients with acute-onset idiopathic dilated cardiomyopathy

Objectives. This study sought to determine whether coronary endothelial dysfunction exists in patients with acute-onset idiopathic dilated cardiomyopathy (DCM) and to explore its relation to recovery of left ventricular systolic function in this patient population.Background. Coronary endothelial dysfunction exists in chronic DCM, but its importance in the development and progression of ventricular dysfunction is not known. To address this issue we studied coronary endothelial function in patients with idiopathic DCM <6 months in duration and explored the relation between coronary endothelial function and subsequent changes in left ventricular ejection fraction (LVEF).Methods. Ten patients with acute-onset idiopathic DCM (duration of heart failure symptoms 2.0 ± 0.4 months [mean ± SEM]) and 11 control patients with normal left ventricular function underwent assessment of coronary endothelial function during intracoronary administration of the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator adenosine. Coronary cross-sectional area (CSA) was determined by quantitative coronary angiography and coronary blood flow (CBF) by the product of coronary CSA and CBF velocity measured by an intracoronary Doppler catheter. Patients with DCM underwent assessment of left ventricular function before and several months after the study.Results. Acetylcholine infusion produced no change in coronary CSA in control patients but significant epicardial constriction in patients with DCM (−36 ± 11%, p < 0.01). These changes were associated with increases in CBF in control patients (+118 ± 49%, p < 0.01) but no change in patients with DCM. Infusion of adenosine produced increases in coronary caliber and blood flow in both groups. Follow-up assessment of left ventricular function was obtained in nine patients with DCM 7.0 ± 1.7 months after initial study, at which time LVEF had improved by ≥0.10 in four patients. Multiple linear regression revealed a positive correlation between both the coronary CSA (r2 = 0.57, p < 0.05) and CBF (r2 = 0.68, p < 0.01) response to acetylcholine and the subsequent improvement in LVEF.Conclusions. Coronary endothelial dysfunction exists at both the microvascular and the epicardial level in patients with acute-onset idiopathic DCM. The preservation of coronary endothelial function in this population is associated with subsequent improvement in left ventricular function.

Relation between single tomographic intravascular ultrasound image parameters and intracoronary Doppler flow velocity in patients with intermediately severe coronary stenoses

Background: Intravascular ultrasound (IVUS) imaging parameters have been suggested as criteria to determine coronary lesion significance before intervention. However, there has not been a systematic examination of combined anatomic and physiologic data in the same patients with coronary artery disease. Methods and Results: To examine the relation between coronary flow reserve and IVUS parameters, 41 patients with intermediately severe coronary artery stenoses had measurements of coronary flow velocity (0.014-inch Doppler flow wire), coronary flow velocity reserve (CVR) (hyperemic/basal mean flow), IVUS imaging (2.9F, Cardiovascular Imaging Systems, Inc.), and quantitative coronary angiography before intervention. Correlations between physiologic and anatomic parameters were performed by simple regression. Results were also examined by patient subgroups with CVR >1.8 or <1.8 to assess differences in IVUS parameters. The angiographic percent diameter stenosis was 52% ± 17% (range 18% to 95%). Mean CVR was 1.88 ± 0.56 (range 0.9 to 3.18). IVUS minimal luminal diameter ( r = 0.312, p = 0.047) and angiographic percent stenosis ( r = 3.05, p = 0.052) were weakly related to poststenotic CVR. Comparing patients with CVR <1.8, IVUS reference segment area, IVUS lumen area, and angiographic percent diameter stenosis was higher (17.7 ± 0.3 vs 12.9 ± 4.4 mm 2, p < 0.05; 6.20 ± 3.76 vs 4.34 ± 2.00 mm 2, p < 0.05; and 60% ± 14% vs 46% ± 17%, p < 0.01, respectively) than in the group with CVR >1.8. Conclusions: Despite a precise determination of cross-sectional vessel areas and absolute dimensions by IVUS, single tomographic measurements did not correlate well with coronary physiologic responses. These data suggest that the physiologic data may be complementary to anatomic quantitative IVUS, enhancing information for coronary interventional decision making. (Am Heart J 1998;135:988-94.)

Comparison of Intracoronary Doppler Guide Wire and Transesophageal Echocardiography in Measurement of flow Velocity and Coronary flow Reserve in the Left Anterior Descending Coronary Artery

Comparison of Intracoronary Doppler Guide Wire and Transesophageal Echocardiography in Measurement of flow Velocity and Coronary flow Reserve in the Left Anterior Descending Coronary Artery

Position control of intravascular Doppler guidewire: concept of a tracking indicator and its clinical implications.

Intracoronary Doppler ultrasound guidewires (DGW) utilize a wide ultrasound beam combined with a measurement of the spectral peak velocity to estimate the spatial peak velocity within a blood vessel. However, the spectral peak velocity may underestimate the true spatial peak velocity if the DGW is not properly positioned. The purpose of this study was to find a Doppler-derived parameter that would aid in the optimal positioning of the DGW within the vessel lumen. We studied the relationship between the time-averaged, spectral-peak velocity (APV) and the normalized first Doppler moment (M1/M0) to develop a DGW position indicator and demonstrate its clinical utility. In vitro, heparinized, human whole blood with a hematocrit of 45% was directed from a reservoir via a roller pump into four serially connected straight silicone tubes of known diameter (2.5, 3.0, 3.5, 4.0 mm). A DGW was inserted into the tubes where simultaneous APV and M1/M0 measurements were obtained for flow rates ranging from 49 to 316 ml/min. Optimal positioning of the DGW was identified at the position where maximum APV and M1/M0 were obtained. With optimal positioning the correlation between APV and M1/M0 was good (APV = 1.62 M1/M0 + 5.0; R2 = 0.98). Importantly, this correlation showed no dependence on the tube diameter. In vivo, in four patients APV and M1/M0 measurements were obtained in 16 coronary artery segments in one left anterior descending, two circumflex, and two right coronary arteries. In 10 vessel segments, there was no discrepancy between the measured and expected M1/M0 after positioning the DGW with help of the Doppler signal quality only. In six vessel segments, repeat DGW positioning using M1/M0 was necessary, yielding an average increase of APV of 20% (7-38%). We conclude that DGW positioning can be optimized using the correlation between APV and M1/M0 as a reference. For any given APV value, there is a corresponding expected value for M1/M0 under the condition of optimal positioning. Any discrepancy between the measured and expected values for M1/M0 then indicates suboptimal positioning.

Which variable of stenosis severity best describes the significance of an isolated left anterior descending coronary artery lesion? Correlation between quantitative coronary angiography, intracoronary Doppler measurements and high dose dipyridamole echocardiography.

This study sought to investigate the angiographic or intracoronary Doppler variables of stenosis severity that best correlate with the results of dipyridamole echocardiography. Quantitative coronary angiography and intracoronary Doppler flow velocity assessments are the commonly used techniques for the objective identification of significant coronary artery stenosis. Thirty patients with an isolated lesion of the left anterior descending coronary artery (LAD) were studied by means of on-line quantitative coronary arteriography, intracoronary Doppler flow velocity measurements and dipyridamole echocardiography 6 months after percutaneous transluminal coronary angioplasty. The quantitative arteriographic analyses were performed on-line; post-stenotic Doppler flow velocities were measured at baseline and after adenosine infusion. Angiographic and Doppler measurements were compared with the corresponding dipyridamole echocardiographic data and analyzed by discriminant analysis. The dipyridamole echocardiographic response was positive in 11 patients (37%). The best cutoff values for predicting an abnormal echocardiographic response were 1) stenotic flow reserve of 2.8 (p = 0.0001); 2) 59% diameter stenosis (p = 0.0001); 3) minimal lumen diameter of 1.35 mm (p = 0.001); 4) coronary flow reserve of 2.0 (p = 0.0002); and 5) maximal peak velocity of 60 cm/s during hyperemia (p = 0.04). Multivariate analysis identified stenotic flow reserve as the only independent predictor of ischemia during dipyridamole echocardiography. Stenotic flow reserve is the variable that best describes the functional significance of an isolated LAD lesion, and a value of 2.8 is the best predictor of a positive dipyridamole echocardiographic response. Furthermore, angiographic variables of stenosis severity relate to echocardiographic test results better than intracoronary Doppler variables.

Evaluation of Coronary Flow Velocity Dynamics and Flow Reserve in Patients With Kawasaki Disease by Means of a Doppler Guide Wire

Objectives. To assess the pathophysiologic effects of the coronary sequelae of Kawasaki disease on coronary hemodynamic variables, we regionally evaluated the flow velocity dynamics and flow reserve in coronary vessels with lesions using an intracoronary Doppler flow guide wire.Background. The pathophysiologic effects of the coronary sequelae of Kawasaki disease on coronary hemodynamic variables have not been completely clarified, and we previously reported some discrepancies between coronary angiographic findings and exercise stress tests in Kawasaki disease.Methods. Doppler phasic coronary flow velocity was determined using an 0.018-in. (0.046-cm) intracoronary Doppler flow guide wire at rest and during the adenosine triphosphate–induced hyperemic response in 95 patients (75 male, 20 female, mean age 9.8 ± 6.2 years) with Kawasaki disease.Results. In 25 patients with coronary aneurysms in 29 vessels, the average peak velocity and diastolic to systolic velocity ratio were significantly (p < 0.05) decreased in the moderate-sized and large-sized aneurysms. Significantly lower values in coronary flow reserve (CFR) were noted in 3 of 10 vessels with moderate aneurysms and in 4 of 7 vessels with large aneurysms. A significant positive correlation (y = 0.53x + 14.6, r2= 0.91) was observed between the percent diameter stenosis evaluated by angiography and that calculated from the flow velocity measurement. However, the percent diameter stenosis calculated from the flow velocity measurement was underestimated compared with that determined by angiography in the stenotic lesions of intermediate severity. A reduced CFR was noted in five of seven vessels with intermediate stenosis ranging from 50% to 75%, and also in three vessels with mild stenosis ranging from 30% to 40%. A reduced CFR was also observed in six of the eight angiographically normal vessels associated with the area of reduced perfusion on exercise thallium-201 myocardial scintigraphy.Conclusions. Abnormalities in flow dynamics and a reduction in flow reserve were revealed in coronary aneurysms of intermediate to large size and in stenotic lesions, even of mild to intermediate severity, in patients with Kawasaki disease. Abnormalities in the coronary microcirculation, as well as epicardial lesions, contribute to the pathophysiologic responses in Kawasaki disease.

Intraindividual Variability of Coronary Flow Reserve in Heart Transplant Recipients With Angiographically Normal Coronary Arteries. A Study With Intracoronary Doppler and Ultrasound

Intraindividual Variability of Coronary Flow Reserve in Heart Transplant Recipients With Angiographically Normal Coronary Arteries. A Study With Intracoronary Doppler and Ultrasound

Intraindividual variability of coronary flow reserve in heart transplant recipients with angiographically normal coronary arteries, a study with intracoronary doppler and ultrasound

Intraindividual variability of coronary flow reserve in heart transplant recipients with angiographically normal coronary arteries, a study with intracoronary doppler and ultrasound